Field of the Invention
The present disclosure relates to an organic light emitting display device (or, OLED) and a method for manufacturing the same. Especially, the present disclosure relates to an organic light emitting display device including active organic light emitting diodes on a flexible substrate and a method for manufacturing the same.
Discussion of the Related Art
Nowadays, various flat panel display devices are developed for overcoming many drawbacks of the cathode ray tube, such as heavy weight and bulk volume. The flat panel display devices include the liquid crystal display device (or LCD), the field emission display (or FED), the plasma display panel (or PDP) and the electroluminescence display device (or ED).
The electroluminescence display device is categorized in the inorganic light emitting diode display device and the organic light emitting diode display device according to the luminescence material. As a self-emitting display device, the electroluminescence display device has the merits those the response speed is very fast, the brightness is very high and the view angle is large. FIG. 1 illustrates the structure of the organic light emitting diode according to the related art. Referring to FIG. 1, the organic light emitting diode comprises the organic light emitting material layer, and the cathode and the anode which are facing each other with the organic light emitting material layer therebetween. The organic light emitting material layer comprises the hole injection layer HIL, the hole transport layer HTL, the emission layer EML, the electron transport layer ETL and the electron injection layer EIL.
The organic light emitting diode radiates the lights due to the energy from the excition formed at the excitation state in which the hole and the electron are recombined at the emission layer EML. The organic light emitting display device represents the video data by controlling the light brightness from the emission layer EML of the organic light emitting diode.
The organic light emitting diode display (or OLED) using the organic light emitting diode can be categorized in the passive matrix type organic light emitting diode display (or PMOLED) and the active matrix type organic light emitting diode display (or AMOLED). Furthermore, according to the direction of the emitted light, it can be categorized in the top emission type and the bottom emission type.
The flexible active matrix type organic light emitting diode display (or Flexible AMOLED) shows the video data by controlling the current applying to the organic light emitting diode using the thin film transistor (or TFT). The display module of the flexible AMOLED is made by that the active matrix type organic light emitting diode is formed on a thin polyimide substrate, then a protective cap, the barrier film, the circular polarization film, and the circuit on film (or COF) for mounting the driving IC are sequentially stacked and the COF is connected to the external PCB, and then the cover plate is attached. During the various films are stacked, some step differences can be occurred. Due to the step differences, the cover plate cannot be assembled in the evenly plane state. In addition, if, due to the step differences, there are some failures when the COF is attached to the display panel, the reliability of the display module can be seriously degraded.